textproduct: Rapid City

KEY MESSAGES

- Hot, above average temperatures will return for the second half of the week.

- Near-critical fire weather conditions are expected today, Thursday, and Friday.

UPDATE

Issued at 912 PM MDT Tue Sep 1 2026

Only minor adjustments to the forecast for the overnight period through Wednesday. The main concern over the next 24-72 hours will be increasingly hot temperatures and near-critical to critical fire weather conditions, especially across NE WY.

DISCUSSION

(This Evening Through Tuesday) Issued at 142 PM MDT Tue Sep 1 2026

Water vapor imagery shows a strong upper wave lifting NE, crossing the Dakotas/eastern MT. Surface analysis shows a surface low across north-central WY. Low level SE flow is drawing increased moisture across central SD, wrapping backwards towards the plains east and north of the Black Hills. Dewpoints are varying widely...from the 40s across parts of NE WY to the 50s over far western SD to around 70 over far SCentral SD. A dryline boundary south of the surface low is expected to slide eastward across SW SD/Neb panhandle late this afternoon and evening. This low level forcing will combine with an upper wave, supporting thunderstorm development. The best instability will be ahead of the dryline across SCentral SD, with MLCAPE reaching 2500 J/kg. Shear is decent enough for supercells, with large hail and damaging winds. Farther west across the SD plains where higher Theta E air has drawn in: some isolated thunderstorms are possible, but not enough instability for severe weather. Severe storms will exit the eastern border of the CWA by mid-evening but could see lingering showers over NE WY/NW SD lingering for a few more hours. Then low amplitude ridging sets up across the region overnight into Wednesday morning, resulting in strong warm air advection. Sunny skies will return and temperatures are expected to top out in the mid 90s across portions of the western SD plains. Temperatures well above average will continue through the end of the week...which could be in the upper 90s Fri/Sat. While isolated thunderstorms can't be ruled out most days, the pattern will be generally dry for the second half of the week.

AVIATION

(For the 12Z TAFS Through 12Z Thursday Morning) Issued At 527 AM MDT Wed Sep 2 2026

A large shield of low stratus and localized BR/fog is well analyzed on satellite and surface weather stations this morning across most of our South Dakota plains, creeping westward into KRAP as of this writing (starting to butt up against the Black Hills). IFR to LIFR cigs/vsbys have been observed and are expected, with low cigs dominating with best coverage and low vsbys more localized. These conditions are predominant at KRAP through 16z/10am, with fairly good consensus between NBM and HRRR guidance in returning the terminal to VFR around that time (give or take 1 hour). Outside of this, hot and dry VFR conditions are expected across the region today and tonight, with breezy southwest winds. Hard to rule out a stray shower or thunderstorm this afternoon and evening just about anywhere, but right now that potential is 10-15 percent. If a storm develops, transient MVFR conditions are possible around any heavier precipitation cores and gusty/erratic winds can be expected with any stronger convective cores.

FIRE WEATHER

Issued At 142 PM MDT Tue Sep 1 2026

Hot and dry weather returns Wednesday through the end of the week with near-critical fire weather conditions expected. Relative humidity may bottom out at 10 to 15 percent on Thursday and Friday across northeastern WY and far southwestern SD. If the likelihood of windy conditions increase, then critical fire weather conditions will be possible. Will continue to monitor.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.